1. Field of the Invention
This invention relates to a covering for an architectural opening, especially a window blind or shade, with two oppositely fixed rails and a movable rail arranged for parallel movement between them.
2. Description of the Related Art
Window coverings are known from GB 2,333,314 which include: a fixed first rail; a movable second rail, parallel to the fixed first rail; a collapsible and extendible blind or shade which is between the fixed first rail and the movable second rail; at least one rotary drive spool mounted on the fixed first rail; at least one driving cord that is wound about the spool with at least one winding and a first drive cord section extending from the spool towards and operatively attached to the movable rail and a second drive cord section extending from the spool in a loop via a fixed surface spaced from the fixed first rail and beyond the movable second rail to the movable second rail where it is operatively attached, and means for reversibly rotating the rotary drive spool to drive the driving cord and to effect movement of the movable second rail to collapse or extend the blind or shade
It is also known, specifically from FIG. 4 of GB 2,333,314, to provide such cord driven blinds with two adjacent cord drive spools. In the embodiment of FIG. 4 of GB 2,333,314, the cord routing of the drive cords is such that the cords extend perpendicular to the axis of the spool such that the cords are easily spooled about the cords spool.
Each cord spool needs to be positioned adjacent the openings of the shade through which is will be threaded. The drive cords and their drive cord sections that are routed through or parallel to the shade, need to be equidistantly spaced along the width of the rails and the covering of in order to assure that the movable second rail during operation of the blind, remains parallel to the fixed rail. In blinds where a plurality of drive cords and cord spools are present and the spools are motor-driven, it is preferred that spools are operatively connected to each other and to the motor, in order for a single motor to drive both spools. This can be a problem in blinds in which additional equipment such as a motor, timer, transformer, infra-red remote control receiver, radio frequency remote control receiver, etc. also has to be in the head rail. In such a case, there is less space in the head rail to organise and place the spools in the proper location in relation to the openings for the cords. Thus situations will occur in which the cord sections extending from a drive spool need to be guided first along a portion of the fixed rail before extending through or parallel to the window covering.
As a solution to this problem cord guides have been used that are positioned adjacent or spaced apart from the driven cord spools. Examples of cord guiding pulleys are shown in U.S. Pat. No. 5,515,898 and U.S. Pat. No. 4,852,627. Different cord routing schemes will result in different parts and positions thereof for the blind.
It is an object of the invention to provide cord guiding means for the drive cords of a blind that can be used for any type of cord routing scheme.